Hagen 6-Pack Fluval Zeo-Carb Ammonia Remover for Aquarium Filter Convenient 6 Pack of 3 (total 18 piece) Fits all Fluval Models Helps protect the aquarium from toxic build-ups of ammonia Adsorbs liquefied wastes, dyes and medications from the water Fluval Zeo-Carb 3x 150 gram 3pk nylon bags x 6pk